What are Polymers? Polymers in Chemistry terms may simply be defined as the high molecular mass compounds whose structures are composed of a large number of simple repeating units and these repeating structural units are obtained from low molecular mass simple compounds what we call as monomers. The chemical process of joining together of a large number of simple and low molecular mass molecules (monomers) to create substantially high molecular mass polymers through covalent bonds is called as Polymerization and hence, the name Polymers.

Remember: Poly= many+ mers= parts; mono= one+ mer= part.

Example: We all might be knowing about the most familiar industrial product called Polyethylene, what we also know commonly as Polythene which finds its use in the manufacture of our common use or household products like pipes, toys, plastic bags, bottles or wire insulators etc. Now when ethylene is heated under pressure with oxygen, we obtain a compound of substantially high molecular mass (about 20,000 or above) in the form of a very long chain in which many ethylene units are attached to one another; end to end and one after the other to which we call as Polyethylene. As such, polyethylene is a polymer of ethylene units and ethylene units in this case are called as monomers. The chemical process in which polyethylene is synthesized is called as polymerization.

 Mankind certainly owes much to the chemistry of polymers. In short, it can be said that man’s life almost revolves around these polymers that may either include natural polymers or synthetic polymers for that matter. While the natural polymers are being synthesized by the biological systems themselves and are thus, called as the biopolymers and include right from the proteins to carbohydrates on the one hand, to starch, cellulose and nucleic acids (DNA/RNA) on the other. At the same time, the so called synthetic polymers are being synthesized artificially by chemical means and include everything from plastics and rubbers to Nylon and Melamine kind of things. The later (melamine) may be known to us as the most familiar thing, we use as melamine crockery that is characteristically known for its unbreakable nature even if thrown down from any height.

Given thus, it can be concluded that there is absolutely no difference whatsoever between the natural and synthetic polymers except their sources of origin and thus, both are synthesized in a similar process what we call as dehydration condensation synthesis that is accompanied by the union of any two monomeric units by the formation of a chemical bond between them to the accompaniment of the loss of a water molecule. Taking advantage of this similarity between the two classes of polymers today, man has started making polymers from biological sources keeping in view the fact that the biopolymers are remarkably known for being biodegradable in nature and thus, non-polluting in nature in contrast to the common synthetic polymers known to be non-biodegradable and thus, highly polluting in nature. This has of late, given birth to the development of biodegradable synthetic polymers that are glaringly known for having their monomeric constituents akin to the biopolymers and lipids and hence, the birth of Green Plastics is the new phenomenon in the world of science in general and the science of Chemistry in particular.

 As stated above, depending on the source of origin of the respective polymers, we can classify all polymers into the following three broader categories:

Natural polymers: Found and derived from the nature only mainly, from plants & animals. The best known examples are Proteins (Polymers of amino acids), Polysaccharides (polymers of monosaccharides), natural rubber (polymers of isoprene), Silk obtained from (silk moth), wool, starch& cellulose etc.

Semi-synthetic polymers: Obtained by using natural polymers by making some modifications in them by artificial means. The best known examples are Nitrocellulose, cellulose acetate, cellulose xanthate etc.

Name of the Polymer	Monomer	Commercial significance or common use
Polyethylene	Ethylene	pipes, toys, bags, wire insulators &bottles etc.
Polyvinyl chloride (PVC)	Vinyl chloride	sheets, water pipes, hoses & hand bags etc.
Polystyrene	Styrene	combs, toys, radio and TV cabinets etc.
Polyacrylonitrile (PAN)	Acrylonitrile	orlon (fibre) and acrilon films
Teflon (Polytetrafluoroethene)	Tetrafluoroethylene	insulators, gaskets and non-stick cookware coatings
Buna rubber	Buta-1,3-diene	tyres, hoses etc.
Polyvinyl acetate	Vinyl acetate	latex paint.
Synthetic rubber or Styrene butadiene rubber(SBR) or BunaS	Styrene	light duty tyres, belting, hoses and rubber soles etc.
Dacron or Terylene	Ethylene glycol	fabrics and magnetic recording tapes.
Glyptal	Ethylene glycol	paints and lacquers
Nylon-6,6	Hexamethylene diamine	fabrics, tyre cords, ropes & carpets etc.
Bakelite	Formaldehyde	electrical goods, phonograph records, fountain pen barrels & combs etc.
Melamine	Formaldehyde	plastic & unbreakable household crockery.

Synthetic polymers: They are essentially and entirely man made polymers and are synthesized in the laboratory and essentially partake the role of Chem.

Why Polymers?  The immense popularity as well as the vast utility of polymers lies in their being studded with some of the unique mechanical properties that include their high tensile strength, elasticity and toughness etc. These properties make the polymers to be a stuff of wide and varied use in industrial as well as domestic applications. Owing to the presence of such unique mechanical properties such as their toughness, durability, elasticity and deformity, today man has been able to synthesize some of the following quality of polymers finding their multifarious applications:

Thermoplastic polymers: A type of polymers which softens on heating and becomes hard on cooling such that it can easily be moulded into various shapes on heating. The polymers such as polyethylene, polypropylene, polystyrene, PVC, Teflon & Nylon etc are the best examples of thermoplastic polymers.

Thermosetting polymers: They are just the reverse of the thermoplastic polymers such that they do not soften on heating rather become hard on heating. Instead, when subjected to a prolonged heating, they start burning. At the same time, like thermoplastic polymers, they cannot be moulded or remoulded into different shapes. Bakelite & Terylene are one of the best examples of a thermosetting polymer.

Elastic polymers or Elastomers: As the name indicates, they are the polymers having an elastic nature or property such that they could easily be stretched out to as much as upto 10 times of their original length and can revert back to their original shape once the force is released. Natural rubber and vulcanized rubber are one of the best examples of elastic polymers or elastomers as such.

Note: The so called Vulcanized rubber containing somewhere, 20-30% of sulphur in it is called as ebonite.

What are Plasticisers?  Substances which are sometimes added to plastics to impart them special attributes such as viscosity, flexibility, softness or some other desired properties so as to obtain the finished products of our choice and of desired qualities are called as plasticizers.

Some of the commercially important & ‘daily use’ polymers, we know by common names are given herein below for more clarity:

Polythene: is a polymer of ethylene and is today, manufactured under two variants called as LDP (low density polythene) which is chemically inert, tough but flexible in nature. Commonly finds its use in packaging, cable insulation, manufacture of pipes, toys and squeeze bottles etc. The second type called as HDP (high density polythene) is comparatively tougher and harder including more tensile strength than that of the LDP. Given thus, it is commonly used in making house wares especially, buckets, containers, dustbins, bottles and pipes etc.

Styron: Chemically called as polystyrene, finds its commercial applications in the manufacture of food containers, cosmetic bottles, TV and radio cabinets, plastic cups & toys etc.

Teflon: Chemically called as polytetrafluoroethylene (PTFE) is a remarkably heat resistant polymer. Owing to this property, it is industrially used in the manufacture of seals and gaskets which have to withstand substantially high temperatures. Being electrically resistant too, it does find its applications in being used as an insulator in electrical items. Yet more importantly, it finds its use in the making of non-stick cook wares as a surface coating. Today, in place of Teflon, PCTFE (polymonochlorotrifluoroethylene) is also being used for the above mentioned purposes.

PVC: A remarkably thermoplastic polymer whose plasticity can be increased by the addition of a plasticizer. It is also an electrical insulator as well as very much resistant to fire and chemicals. As such, PVC is commonly used for making sheets, pipes, waterproof outer clothing i.e. rain coats, hand bags, table clothes, plastic dolls, gramophone records, floor covering as well as to provide electrical insulating coating on electrical cables.

Orlon: Also called as acrilanor courtelle, used in making water resistant and quick drying fibre which can be worn or may even be blended with wool and is thus, used in making anything from clothes to carpets to blankets etc.

PMMA (Polymethylmethylacrylate): A remarkably hard and transparent polymer and commercially known as Plexiglas.  It finds its use as being hard and transparent in making lenses, photosensitive articles, aircraft windows, skylights and plastic jewellery etc. Its variant called as PEA (polyethylacrylate) is sometimes used as an alternative of rubber but, mainly finds its use in blankets and carpets.

Dacron: Commonly known also as Terylene but more famously as polyester. Being most important of all the polyesters, it can easily be spun into fibres on being mixed with either cotton or wool. Moreover, it defies moisture absorption and thus dries up soon. Terylene clothes or fabric is not only strong, flexible and durable but is noted for retaining almost permanent or long lasting creases on them as well. Dacron when made into a sheet or a film, it shows a remarkable tensile strength and resists tearing and thus, its films are being used for making magnetic recording tapes.

Nylon: Nylon infact is a general term given to all those polymers that are essentially polyamides and as such, have their structure exactly like the protein molecules. Since, all nylon polymers are synthesized in a similar dehydration condensation synthesis process and are the universal product of diamines and dibasic acids. The only difference in different nylon polymers remains with respect to the number of carbon atoms present in their constituent diamines & dibasic acids. This is usually represented by suffixing a number with the name of the particular nylon. For example: Nylon-6,6 read as Nylon six, six is a polymer that is synthesized with hexamethylene diamine having six carbon atoms & adipic acid, a dibasic acid again having six carbon atoms and hence, the name nylon 6, 6. Similarly, we have another synthetic nylon polymer called as nylon 6,10 and so on. Nylon fibres are being stronger than the natural fibres thus are commonly used for making ropes and cords etc. though, also used in making carpets& fabrics too.

Melamine: A commercially well known polymer, used in making plastic, unbreakable household crockery and sold under the name of melamine only.

Bakelite: Chemically called as phenol-formaldehyde resin, is used extensively for making combs, phonograph records, fountain pens & electrical goods etc. Soft bakelite is used as binding glue for laminated, wooden plants including in varnishes & lacquers etc.

Neoprene: It was the very first synthetic rubber manufactured on a large scale and is also called as dieprene and is a polymer of its basic monomeric sub-unit called as chloroprene. In terms of its mechanical properties, it is very much similar to the natural rubber called as isoprene, but neoprene is comparatively more resistant to the action of oils, gasoline including to sunlight and heat etc. Owing to this property, neoprene finds its application in the manufacture of automobile, refrigerator parts alongside making hoses for petrol and oil containers etc.

Thiokol: A chemically resistant polymer and is used extensively in the manufacture of engine gaskets. Yet its most important use has been found in its being used as rocket fuel when mixed with a suitable oxidizing agent like oxygen.

Buna-S: A polymer that is by nature or property is an elastomer in which ‘Bu’ stands for butadiene; ‘na’ stands for sodium being used as a polymerizing agent and ‘S’ stands for styrene. It is famous as being a general purpose styrene rubber, designated as GRS. It is generally subjected to vulcanization so as to make it extremely resistant to wear and tear and is therefore commonly used in the manufacture of tyres and other mechanical rubber goods. There is also one Buna-N which is commonly called as general purpose rubber Acrylonitrile, designated as GRA that is noted for being even more rigid and being more resistant to the action of petrol, lubricating oil including many organic solvents and is thus commonly used for making fuel tanks.

The Birth of Biodegradable Polymers:

The greatest disadvantage of the synthetic polymers is their being non-biodegradable in nature that means, they resist the natural forces of degradation and are thus highly polluting in nature. This has been a greater cause of concern for the world environmentalists until; they stumbled upon the possibility of synthesizing the so called bio-degradable polymers. This became possible when the scientists discovered that the best way to produce the bio-degradable polymers through synthetic means is to insert a hydrolysable ester group into a polymer. This is exactly similar to the synthesis of fats or lipids inside our body which are essentially called as the esters of fatty acids. Today, the synthetic biodegradable polymers have given us a wonderful option to replace the traditional petroleum based polymers such as plastics which are not only non-biodegradable, but have been a major source of environmental pollution. At the same time, the biodegradable polymers have made it possible to use them in a host of such products which human beings consume in the form of medicines such as capsules and they very well get degraded inside the body of human beings by way of enzymatic hydrolysis or by simple oxidation. Owing to this property, biopolymers today find extensive applications in the industries such as cosmetics, pharmaceuticals, textiles and packing industry etc. mainly for the reason that these synthetic biopolymers are synthesized by inserting the same functional groups as are prevalent in the natural biopolymers such as in lipids and thus, behave exactly like the natural biopolymers so far as their degradation or breaking up by the body enzymes is concerned.

In the more explicit terms, the most important class of synthetic biodegradable polymers that the Chemistry of polymers has given us today, are being classified under following two categories:

• Aliphatic polyesters.
• Aliphatic polyamides.

Aliphatic polyesters: In this category, the most important synthetic biodegradable polymers finding extensive industrial applications are the following three:

PHB (Polyhydroxy butyrate): This biodegradable polymer is obtained from 3-hydroxy butanoic acid that acts as its monomer. Through dehydration condensation that is a universal process of polymerization, we get PHB.

PHBV (Polyhydroxy butyrate- CO-hydroxyvalerate): This is a copolymer of two different monomeric units respectively called as 3-hydroxy butanoic acid and 3-hydroxy pentanoic acid such that two different monomers are thus joined by an ester linkage formed following the loss of a water molecule. This ester bond so formed is exactly the same way as the one formed in the formation of a polynucleotide of a DNA/RNA molecule in which a pentose sugar is esterified to a phosphoric acid thereby, forming a phospho ester bond.

Noted that both PHB and PHBV are being extensively used for making films for packaging purposes most importantly, around the drug capsules and medicine wrappers. When a drug is enclosed in a capsule of PHBV, the biodegradable nature of PHBV makes it to be degraded easily inside the body thereby, releasing the drug enclosed inside. Not only this, PHBV is also subjected to bacterial degradation out in the environment as well.

PGA (Poly glycolic acid) & PLA (Poly lactic acid): This synthetic and biodegradable co-polymer is commercially called as Dextron. Noted that this copolymer of PGA & PLA became the first ever biodegradable polymer to be used for stitching of wounds on an operation table. Even today, this is extensively used in operative surgeries owing to the fact that this polymer easily gets degraded and is completely absorbed within the body say, within 15 days to one month of the surgery or the wound being stitched with.

Aliphatic Polyamides: In this category following two synthetic biodegradable polymers have become quite famous:

• Nylon-2-Nylon-6;
• Poly-caprolactone lactone(PCL)

 What is a Dye? A dye is either a natural or synthetic colouring matter which is used in a solution form to stain or colour materials, most commonly fabrics.

However, it must be noted that all colored substances are not dyes. And, a coloring substance can only be called a dye once; it fulfills the following three conditions:

It must have a suitable color;

It could be fixed onto the fabric either directly or with the help of a *mordant

When fixed, it must be fast to light and washing which means that it must be resistant to the action of water, acids and alkalies rather being resistant most importantly to alkalies just because, the washing soaps and detergents are nothing, but have an alkaline nature as such. At the same time, a dye must not give away its color when exposed to sunlight howsoever, bright the sunlight may be.

A mordant is any substance which can be fixed onto the fabric and reacts with the dye to produce color on the fabric. Given thus, it can be stated that all colored substances can not necessarily be described as dyes unless; it fulfills the criteria given above. For example, Azobenzene although, a highly colored substance, but it does not act as a dye just because, it does not fix itself onto a fabric. In contrast to this, two other almost related substances called as para-aminobenzene and para-Hydroxy-azobenzene do act as dyes. The rationale behind this can be explained by a famous theory called as Chromophore-Auxochrome Theory, propounded by a chemist named Otto Witt in 1876. This theory states that:

The color of a substance is due to the presence of certain multiple bonded groups in it what we call as chromophores (chroma = color; phorein = to bear).But the mere presence of a chromophore is in itself not sufficient for a substance to be colored. Thus, it does require the presence of an additional group which should be attached to chromophore and resembles in having an extensive system of alternate single and double bonds exactly the way they are found in aromatic benzene like compounds. The presence of such groups as being attached to the chromophore thus makes the chromophore part of a colored substance to absorb certain wavelengths of the white light and reflect back complementary colors and hence, we see a substance in a particular shade of the color or colors as such.

That there are certain functional groups which can not produce any color on their own, but they certainly contribute to intensifying the color of a substance when found present along with the chromophore part of a substance. Such color enhancing groups are called as auxochromes. (Gk. Auxanien = to increase; Chroma = color). In short, such functional groups (auxochromes) when are being attached to the chromophore, make the color deep and fast and thus, fix the dye onto the fabric. The typical examples of some of these “auxochrome” functional groups may be given as: Hydroxy group, Sulphonic group, Carboxylic group, Amino group and Alkylamino and Dialkylamino groups etc.

In the same vein, some of the typical examples of important “chromophores” may be given as: Azo, Nitro, Carbonyl, Thio carbonyl, Dicarbonyl and Ethylenic etc.

Therefore, taking these postulates of the theory into consideration, we can certainly reason out as why do the substances such as para-aminobenzene & para-hydroxy-azobenzene really act as the colored dyes and why not a much related substance called as Azobenzene defies at being a dye.

Classification of Dyes: Today, there is two fold classification of dyes that is being followed at. While the Chemists classify the dyes on the basis of the chemical structure a dye has. The dyers however, classify the same on the basis of their application. Let’s discuss and exemplify each type as below:

?Classification of Dyes on the basis of their chemical structure: On this count, we have following kind of dyes:

Nitro & Nitroso dyes: In this category, the important example of dyes are:

• Picric acid
• Gambine-Y
• Gambine-R
• Martius yellow
• Naphthol yellow-S and
• Naphthol green-B etc.

Azo dyes: Azo dyes constitute the largest as well as the most important group of synthetic dyes. These are also noted for being the highly colored dyes. Some of the important examples of these Azo dyes are as below:

• Bismark brown
• Methyl orange
• Methyl red
• Congo red
• Aniline yellow
• Butter yellow

Triarylmethane dyes: These are so called as triarylmethane dyes because, structurally these dyes have a central carbon atom that remains bonded to three aromatic rings. The most important examples under this class of dyes are as below:

• Malachite green
• Rosaniline and
• Crystal violet.
• Anthraquinone dyes:
• Alizarin is a typical example of this class of dyes.
• Phthalein dyes: The important dyes of this class include the following:
• Phenolphthalein
• Fluorescein
• Eosin
• Mercurochrome etc.

Indigo dyes:  In this class, Indigo is the oldest known dyes in the world. This class of dyes includes some of the following well known dyes:

Indigo that is available in the form of a dark blue crystalline powder.

Tyrian blue that is available in the form of a royal blue color and is a dibromo derivative of Indigo.

?Classification of dyes on the basis of their Application: On this basis, we have the following classification of dyes:

Direct dyes: These dyes can be applied directly onto the fabric that may be of plant (vegetable) or animal origin by simply dipping the same into the hot aqueous solution of the dye and thus, are referred to as the direct dyes. These dyes are most useful and productive for the fabrics especially, cotton, rayon, wool, silk and nylon etc. Some of the prominent examples of this class of dyes are:

Martius yellow and Congo red.

Acid dyes: These dyes have sulphonic acid as an important constituent, the presence of which makes these dyes as being water soluble in nature. These can be applied to wool, silk and nylon etc. Its best known example is:

Orange-1(Azo dye) that is an excellent dye of this group.

Basic dyes: These dyes have hydrochlorides or zinc chloride salts as their constituent and can be used for coloring both nylon and polyester fibres. Some of the important dyes of this group are:

• Aniline yellow;
• Butter yellow;
• Magenta (rosaniline) and
• Malachite green etc.

(Note): Both acid and basic dyes are nothing, but are actually direct dyes for all practical purposes.

Mordant dyes: So far the very nature of these dyes is concerned, these dyes have no natural affinity for the fabric concerned and are thus, attached to the same with the help of certain additional substances what we call as mordants. As stated earlier, a mordant is any substance which can be fixed onto the fabric and hence, reacts with the dye to produce desire color or colors on the fabric. There are three types of mordants that are being used commonly:

Acidic mordants such as tannic acid which are used with basic dyes.

Basic mordants such as metallic hydroxides or albumin, used with acidic dyes &

Metallic mordants such as salts of aluminium, chromium, iron or tin etc which are also used with acidic dyes. Actually, the action of a mordant is based on the fact of its forming an insoluble coordination compound between the fabric and the dye and thus, binds the two. However, the process of mordant dyeing consists of impregnating the fabric with the mordant in the due presence of a wetting agent followed by dipping the fabric into a solution of the dye. In this regard, Alizarin presents a typical example of a mordant dye which gives different colors with different metal ions used. For example, with aluminium, alizarin gives a rose red color, with iron, it gives a violet color and for that matter, with chromium, it gives a brownish red color.

Vat dyes: As these dyes are insoluble in water and thus, cannot be applied directly. Infact, Vat dyes refer to a class of dyes which are applied onto a fabric, but always in the colorless reduced state and then are oxidized to a colored state. While, the said oxidation is achieved either by simply spreading the fabric open in the air or by treating the same with some oxidants such as perboric acid. The colorless and reduced state of the dye is called as the Leuco base. Vat dyes are most commonly used on cotton fabrics and include the following two most prominent examples:

• Indigo and
• Tyrian purple etc.

What is a drug? The word ‘drug’ is derived from a French word called ‘drogue’ which means a ‘dry herb’. In fact, in a general way, a drug may be defined as a substance that is used for the prevention, diagnosis, treatment or the cure of a disease in man or other animals. Although, a drug may either be a single chemical substance or a combination of two or more different substances yet, an ideal drug should invariably satisfy the following criteria essentially:

A drug when given or administered to an ailing individual or host, its action should be localized at the site where it has been desired to act. But in actual practice, there is practically no drug that could behave in this manner.

It should act on a system with efficiency and safety.

It should have minimum side effects.

It should not injure host tissues or physiological processes for that matter.

The cells or body system should not acquire or develop resistance to the drug after some time.

But as a matter of fact, very few drugs satisfy all the above requirements just because, each drug has an optimum dose and below which it has no effect and above this level, it becomes a poison.

What is chemotherapy? The term ‘chemotherapy’ has its literal meaning in ‘chemical therapy’ or chemical treatment which simply refers to the use of drugs and medicines to cure the body of the diseases or their symptoms. The term was coined in 1913 by Paul Ehrlich, a German chemist to refer to the use of drugs or medicines for treatment purposes, who is today regarded as the father of modern chemotherapy. In his own words, he defined chemotherapy as:

“The use of chemicals (drugs) to injure or destroy infectious micro-organisms without causing any injury to the host.”

Given thus, according to Paul Ehrlich, chemotherapeutic agents are chemical substances which have selective toxicity, being harmful as much as possible to the invading or infectious organisms, but harmless to the host. Chemotherapy today has developed into a vast subject and efforts are being continuously made to search new and new drugs so as to free human beings from various types of diseases.

Noted that the chemicals or drugs used in chemotherapy are usually classified into various categories on the basis of their specific action and effect on the body of a person. On the basis of this criterion, we have the following classification of the chemical drugs that is what the discipline of chemotherapy knows them all today:

ANTIPYRETICS & ANALGESICS

What are Antipyretics? An antipyretic is a drug which is responsible for lowering the temperature of the feverish organism/ person to normal, but without affecting the normal temperature states of the body. As we know, the CNS, especially the Hypothalamus, plays an important role in maintaining a balance between the heat production and heat loss from the body so as to regulate the normal body temperature. This why that Hypothalamus is referred to as the thermostat of the body. In cases of fever, there still exists a balance between heat loss and heat production, but the thermostat is only set at a higher temperature essentially for biological reasons. The antipyretic drugs in fact, help to reset the thermostat back to normal temperature in a way that the heat production is not inhibited at all, but heat loss is increased by virtue of an increased peripheral flow of blood which thus, increases the rate of perspiration. This all causes body to lose heat and subsequently lowers the body temperature. Some of the important antipyretics are being exemplified below:

Aspirin: This is one of the well known antipyretics, chemically called as Acetyl salicylic acid. Aspirin is absorbed from the gastrointestinal tract wherein the stomach acid causes a partial hydrolysis of the ester. The said ester then circulates in the blood and its further hydrolysis occurs to yield salicylic acid which is the active component of the drug. Although, aspirin has long been known to be an effective antipyretic as such, but it does cause some side effects that may include stomach ulcers to the extent of even becoming a cause of bleeding. This is why; it is always admonished that the aspirin should not be taken empty stomach. Some persons are even found to be allergic to aspirin and such allergic reactions generally manifest as rashes on skin, lowering of blood pressure, profuse sweating, intense thirst, nausea and vomiting etc. Aspirin is also used to prevent heart strokes because it acts as a potential vasodilator as well. Some other commonly used and well known antipyretics are: Phenacetin, paracetamol, novalgin and phenyl butazone etc. Besides these, the derivatives of Para-aminophenol are also used as antipyretics, but unfortunately, they have a limitation in the sense that they act on the RBC’s and thus, may prove to be harmful even in smaller doses.

What are Analgesics? The drugs which relieve the body of pains or the drugs that act as pain killers are called as analgesics. Depending upon the source of their origin, the analgesics are being classified into two categories:

Narcotic (addictive) drugs: These mainly include opium or its various derivatives such as morphine, codeine, marijuana and heroin etc. These have their effect in producing what we call as analgesia and thus, induce sleep to relieve the body of severe pains. In higher doses, these may even cause unconsciousness as well. Being very potent drugs, their prolonged use leads to addiction at the end of the day.

Non-narcotic (non-addictive) drugs: Being not that much potent, these drugs do not cause addiction and thus, are most commonly used as analgesics. Common analgesics in this category include the synthetic drugs such as aspirin, analgin, novalgin, butazolidine (phenyl butazone) and brufen (ibuprofen) & diclofenac sodium etc. Noted that these all analgesics also have antipyretic property.

ANTISEPTICS & DISINFECTANTS: The chemicals used for sterlisation purposes are collectively called as antiseptics & disinfectants with a little shade of difference between the two from the view point of their application and use.

What are Antiseptics? An antiseptic is a substance which prevents the growth of micro-organisms as long as it remains in contact with them. In fact, the word ‘septic’ is derived from a Greek word- septikos which means to putrefy or rot. In the world of medicine, it indicates the state of being infected with pus forming organisms. And, all those anti-infective chemical agents which are applied locally that means those chemicals that are applied directly onto the skin wound or else, are referred to as antiseptics. Some of the common examples of the most popular antiseptics are: Dettol, savlon, acriflavin, gentian violet, mercurochrome, boric acid, chloramines-T, tincture of Iodine, iodoform and Potassium permanganate etc.

(Note): Tincture of Iodine: Is an alcohol water solution containing 2-3% of Iodine.

Dettol: Is one of the most commonly used antiseptics in the world. In its chemical composition, it is a mixture of two substances called as chloroxylenol and alpha-terpeneol. While, chloroxylenol which in strict chemistry terms, called as (4-chloro-3, 5-dimethyl phenol) can be used both as an antiseptic as well as disinfectant. One of its derivatives called as para-chlorometaxylenol is popularly used as body deodorant.

What are disinfectants? Those chemical substances which are either used to kill the disease causing micro-organisms or to stop their growth and multiplication are called as disinfectants. Since, these chemicals are harmful to the living tissues and cannot be applied directly onto the live skin therefore; these are always used for the sterilization of inanimate or non-living objects such as surgical instruments, utensils, clothes, floors, sanitary fittings, sputum & excreta etc. Some of the common examples of disinfectants are: phenol, methyl phenols, hydrogen peroxide, chlorine, bleaching powder & sulphur dioxide etc. Noted that even the same substance can be used both as an antiseptic and disinfectant depending upon the concentration of that very substance in the solution say for example, 0.2% concentration of phenol in a solution makes it to act as an antiseptic whereas, 1% solution of the same makes it to display the characteristic of a disinfectant.

Amongst many, some of the popular examples of disinfectants may be stated as below:

Chlorine: A common disinfectant used in drinking water where it is used in the concentration of 0.2 to 0.4 ppm (parts per million).

Hexachlorophene: A disinfectant mainly used in soaps & creams etc.

Thymol: A natural derivative of phenol is also a powerful disinfectant.

Amyl meta cresol: Generally used as an antiseptic in mouth wash or gargles etc.

Bithional: A common antiseptic in medicated soaps which are generally recommended for use to do away with the undesirable odours produced by bacterial action on skin or other body surfaces.

Gentian violet and methylene blue: Though are the well known organic dyes, but can be used as effective antiseptics.

ANTIBIOTICS: What are Antibiotics? The chemical substances produced by or derived from the living organisms and are capable of inhibiting the life processes or even killing or destroying the other disease causing micro-organisms are called as antibiotics. In fact, the word, antibiotic is derived from the term ‘antibiosis’ that means-“survival of the fittest” in a process in which one organism may destroy or kill another in order to preserve itself. In short, the use of one organism against the other by means of chemical substances produced or extracted from the one to harm or kill the other is called as an antibiotic.

Who does not know about the famous wonder drug called as Penicillin, discovered by British bacteriologist, Alexander Flemming in the year 1929 from a fungus/mould, Penicillium notatum that was introduced into the medical practice later in 1941. Today, although, a number of naturally occurring penicillins have been isolated yet, all of these are noted for having the same empirical formula given as: C9H11O4SN2R; where the value of R is different in different penicillins. Today following types of penicillins have been isolated and known by their respective chemical names as given in the table below:

Name of the Penicillin	Chemical nam
1.Penicillin-F or I 2.Penicillin-G or II 3.Penicillin-X or III 4.Penicillin-K or IV 5.Penicillin-Y or V 6.Ampicillin 7.Methicillin 8.Amoxycillin	2-Pentenyl penicillin Benzyl penicillin p-Hydroxy benzyl penicillin n-Heptyl penicillin Phenoxy methyl penicillin
	(Note): Of all the Penicillins known today, Penicillin-G is the most commonly used

Almost, all the penicillins are only sparingly soluble in water. However, their sodium or potassium salts are very much soluble in water. So far their antibiotic property is concerned; all penicillins have been found to be quite effective against all Gram positive strains of bacteria, but not effective against Gram negative strains as such. Similarly, most of the organisms generally develop resistance against Penicillins and thus, they have lesser toxicity as compared to the sulpha drugs. At the same time, Penicillins can induce allergic reactions in some individuals and thus, penicillins are always given after a test prick.

Classification of Antibiotics: Antibiotics can be either of the following two types:

Bactericidal: Those which can kill the disease causing bacteria. Bactericidal antibiotics are: Penicillin, oxloxacin, aminoglycosiders etc.

Bacteriostatic: Those which does not kill bacteria, but can arrest their growth or multiplication. Examples are: Tetracycline, chloramphenicol and erythromycin etc.

It may further be noted that of all the antibiotics discovered till date, some of them are described as being narrow spectrum antibiotics whereas, others are strictly so called broad spectrum antibiotics in the sense that they are effective against a number of other disease causing micro-organisms as against the narrow spectrum that are effective against a particular disease causing bacteria only. Some of the most prominent broad spectrum antibiotics may be described as below:

Streptomycin: Discovered in 1944 by Waksman, this broad spectrum antibiotic has been found to be more effective against TB though, also used for other common infections such as infections of throat, lungs, ears or kidneys. It is also very effective against pneumonia and meningitis. Chemically, it is an amino base and forms salts that are quite soluble in water. Streptomycin is rapidly absorbed after an intramuscular injection and thus, oral administration of this serves no use.

PAS (Para-amino salicylic acid): PAS along with INH (iso-nicotin hydrazine or isoniazid) both are used for the treatment of TB also.

Chloramphenicol: A well known broad spectrum antibiotic first isolated from a species of streptomyces. Now it has been produced synthetically on a commercial scale. It tastes bitter and appears as grayish white or white crystals. It is effective against gram positive and gram negative bacteria both including against some viruses as well and as such is given for the infections right from typhoid to para-typhoid fevers including for diarrhea, dysentery, influenza, whooping cough (pertusis) and urinary tract infections as well.

Tetracyclines: These are also broad spectrum antibiotics may be used against almost every kind of pathogen right from bacteria, viruses, protozoans etc and can be taken orally as well.

ANTIMICROBIALS: What are antimicrobials? The chemical substances that are used to cure diseases caused by any type of pathogens right from bacteria, fungi to viruses are called as antimicrobials. Given thus, antimicrobials may include anything from antibacterials to antifungals up to antiviral agents. Some of the most prominent examples of antimicrobials may be stated as sulpha drugs, antibiotics and quinolones etc.  

Sulpha drugs: A group of synthetic drugs that are the chemical derivatives of para-amino benzene sulphonamide, so called commonly as, Sulphanilamide are called as sulpha drugs. In fact, sulpha drugs were the first ever chemotherapeutic agents to be widely used for the cure of bacterial infections in human beings. However, today, they have been replaced by antibiotics so far as the treatment of bacterial diseases is concerned. Some of the successfully used sulpha drugs have been given in the table below:

Name of the sulpha drug	Used to cure
Sulphapyridine Sulphadiazine Sulphaguanidine Sulphathiazole Succinyl sulphathiazole Sulpha acetamide	Pneumonia Pneumonia, throat infections & meningitis. Bacillary dysentery Staphylococcal infections,  bubonic plague. Intestinal infections  and cholera Urinary tract infections.

ANAESTHETICS: What are anaesthetics? The drugs or chemical substances that can produce insensibility to the vital functions of all types of cells or tissues by virtue of suppressing the pain feeling area of the CNS are called as anaesthetics. In terms of their effect on the body, they produce a kind of reversible effect in the sense that the affected organs return to their normal state as soon as the concentration of an anaesthetic is decreased. Thus, it can be said that the anaesthetic substances produce a temporary insensibility to pain or feeling of pain either in the whole body or just only a part of it. On the basis of their effect on the body, anaesthetics are being classified into the following two main categories:

General anaesthetics: They are used for anaesthesiasing the whole body in the sense that these depress the CNS to an extent that all sensitivity to pain or having a feeling of it is lost and hence, produce unconsciousness all over the body. The general anaesthetics are generally used during major surgical operations. However, they may be used either in the form of a gas or may be administered as liquid in injectible form. General anaesthetics being used in gaseous form commonly are nitrous oxide, cyclopropane, ethylene, ether (most popularly, diethyl ether). However, the one that is being used as an injectible anaesthetic is called as sodium pentothal.

(Note): Sodium pentothal is also famous for being used in “narco tests” or narco analysis, an interrogatory tool used by the police to make the suspect reveal the truth.

Local anaesthetics: These are noted for having a local effect and thus, affect only a part of the body to make the same insensitive to pain or feeling. Therefore, local anaesthetics are used for performing small surgical operations only such as tooth extraction, wound stitching or applying an incision to an abscess etc. Some of the common local anaesthetics being commonly used in the medical practice are xylocaine (used in jelly form), ethyl chloride (used in spray form) and procaine (used as an injection). Today, some other modern local anaesthetics are also being employed for the purpose such as alpha-eucaine, orthocaine and dimethisoquin etc.

TRANQUILLIZER or HYPNOTICS: What are tranquillizers? The chemical substances that are used to relieve a person of mental anxiety and thus, reduce mental tension and consequently, have the affect of bringing about a calm and composed outlook in a person are called as tranquillizers. Noted that the effect of tranquillizers is not associated with producing any degree of sedation or hypnosis in a person nor is there any alteration in the level of consciousness of a person. It is said that the tranquillizers are generally recommended and hence, effective against such mental disorders when ordinary hypnotics or sedatives fail to yield any result in a person concerned. Since, these drugs are used against serious mental disorders therefore; they are also called as psychotherapeutic drugs.  The earliest examples of well known tranquillizers were reserpine (an alkaloid, derived from spineless cactus) and chlorpromazine. Today, however, following drugs are most commonly used as tranquillizers such as barbituric acid and its derivatives, what we collectively call as barbiturates for example, veronal, amytal, luminal, equanil, seconal, Librium, diazepam that is available in its forms called as valium and calmpose. Of these, equanil is most commonly used as a medicine for mental depression and hypertension etc.

Noted that besides, the above tranquillizers, following other kind of drugs are also being used for the cure of mental diseases which in all, may be broadly classified into the following categories:

Narcotics: These are noted for having both the properties of an analgesic and a depressant. In the later capacity, they can reduce anxiety as well as mental tension. Examples are: Pethidine, heroin and opium and its various refined derivatives.

Hypnotics: These are simply tranquillizers in action & effect.

Sedatives: Also called as depressants, used for serious mental ailments particularly, given to such mental patients who exhibit a violent bahaviour so that they can induce a feeling of relaxation, calmness by bringing in drowsiness in them. Some of the common sedatives being used are valium and barbiturates.

Antidepressants: Commonly called as mood boosters and are generally given to such people who exhibit a lack of confidence in them such that these induce a feeling of well being in them. Some of the common examples of antidepressants are vitalin, methadrine and cocain.   

ANTI-MALARIALS: The medicines or chemical substances that are used to bring down body temperature during a malarial fever or attack are called as anti-malarials. Originally, it was only one drug derived from the bark of a plant, Cinchona and called as quinine (an alkaloid) was known to be an effective anti-malarial drug. Although, a number of species of malaria pathogen (a protozoan called plasmodium) has been discovered, but there are only four species of this parasite that are known to cause malaria in human beings. These four pathogenic species are Plasmodium vivax, P. malariae, P.falciparum and P.ovale. Given thus, following four types of malaria occur in human beings as given in the table below:

Pathogen type (Plasmodium species)	Malaria characteristics (Fever periodicity)
1. Plasmodium vivax	Fever on alternate days.
2.Plasmodium ovale	Fever once in three days.
3. Plasmodium malariae	Fever once in three days.
4. Plasmodium falciparum	Fever once in four days.

Chemotherapy of malaria: The chemotherapy of malaria is always connected to the different stages that the malarial parasite has in its life cycle. The complete life cycle of the malarial parasite is however, prominently characterized for having two distinct stages called as asexual and sexual which it completes in two distinct hosts called as man and female anopheles mosquito respectively. As the female anopheles bites a human being, it injects the parasite into the human body at a stage called as sporozoite. The sporozoites immediately go or travel down to liver, where it completes its asexual life cycle by undergoing a series of multiplication divisions (sporulation). From the liver, after rupturing the liver cells, the plasmodium parasite migrates down into the blood stream and enters the RBCs where it again undergoes repeated multiplication divisions (asexual reproduction) ending up rupturing the RBC thereby, releasing a toxic substance into the blood called as haemozoin that is what responsible for a spate of chills and fever in a malaria infected individual. It is well within the RBCs only that the parasite undergoes its sexual stage partially that is accompanied with the formation of gametes called as gametocytes.   Now these gametocytes are taken up by the female mosquito with its blood meal from the infected person where in the body of the female, the sexual reproduction ultimately completes by the act of fertilization that occurs in the intestine of the female. The zygote thus formed also develops fully to the infective stage of sporozoite well within the intestine only. From the intestine then, these sporozoites are released and escape up into the salivary gland of the female from where they could go to any other healthy person when the same female mosquito bites a healthy person and releases the sporozoites into the body (blood) of an individual and the same cycle repeats again…

Given thus, the choice of an anti-malarial drug depends on what stage or point of the life cycle of the malarial parasite it is being intended to hit at. Some of the common chemical anti-malarial drugs being used as:

• Primaquine: It is used to kill or destroy sporozoites in the liver. However, this drug is too toxic to be recommended for a long term use.
• Chloroquine: Used to kill the parasite in the blood.
• Proquanil:       …….Do…
• Pyrimethamine……Do….

ANTACIDS: What are antacids? As we already know that the environment of Stomach is extremely acidic due to the secretion of HCL during the process of digestion. Sometimes, the HCL secretion in the stomach gets unduly increased thereby creating problems of stomach ulcer, gastric reflux and oesophagitis etc.what otherwise; we call as acidity which can be cured by making use of certain chemical substances. Hence, the chemical substances or compounds which reduce or neutralize acidity in the stomach are called as antacids.

Some of the commonly used antacids are given herein below:

• Baking soda containing sodium bicarbonate and potassium bicarbonate.
• MgO, MgCO3 and Magnesium trisilicate etc.
• Calcium carbonate and Aluminium amino acetate etc.

Noted that all antacid compounds are essentially basic in nature they therefore, neutralize HCl in an ordinary chemical reaction, releasing water molecules at the end of the reaction. The antacids can be used either in the liquid form or in the form of tablets, but solution form of the antacids has been found to be more effective.

In the world of chemotherapy, following two chemical drugs have been found to be very effective in the treatment of peptic ulcers.

• Ranitidine, commonly called as Zantac.
• Cimetidine, commonly called as Tegamet.
• Similarly, following two are the new drugs that are being used to inhibit the gastric secretions and hence, to control acidity as well:
• Pentaprazole &
• Omiprazole…

ANTI-HISTAMINES: What are anti-histamines? The connective tissue in the human body is noted for having specialized cells especially, in between and around the blood capillaries called as Mast cells. These mast cells have a significant role to play in defending the body against anything that comes from outside into the body in the form of antigens or else by showing allergic reactions against them. These allergic reactions are manifested in the form of certain chemical substances released by the mast cells into the blood called as histamines. Hence, the chemical substances or the drugs that we use to either diminish or do away with the effect of histamines during an allergic reaction are called as anti-histamines. In the world of medicine, the most effective and popular anti-histamines being used are as given below:

Diphenhydramine commonly called as Benadryl.

• Pheniramine maleate, commonly found in Avil and cough syrups.
• Chloropheniramine maleate (Zeet)
• Triprolidine (Acididil)
• Phenothiazine & Promethazine (Phenargan)
• Dimethindene (Foristal)
• Antazoline (Antistine) &
• Chlorotheopyllinate salt (Avomine).

Note: These all drugs besides being effective anti-histamines are also used in the treatment of severe allergic reactions such as hay fever, mild asthmatic attacks, insect bites and cold etc…

The chemicals used in the edible food items generally take the following forms:

• The food preservatives.
• The edible colours.
• Artificial sweetening agents and
• Anti-oxidants etc. Let’s discuss their chemistry in brief herein below:

The Food preservatives: A preservative may be defined as a substance which is capable of inhibiting or arresting the process of fermentation, acidification or for that matter, any kind of decomposition of the food items. Depending upon their course of action, the food preservatives are being classified into following three categories:

Anti-oxidant preservatives: These are the substances that retard the chemical reactions as well as the breakdown of the food items when they come in contact with the oxygen, light, heat and certain metals. These chemicals, however also stabilize some of the vitamins and amino acids present in food items. Some of the prominent examples of anti-oxidant food preservatives are:

BHA (Butylated Hydroxy Anisole). The addition of BHA to butter can increase its storage life from months to years.

• BHT(Butylated Hydroxy Toluene)
• Tertiary butyl hydroquinone(TBHQ)
• Gallic acid and
• Propyl gallate (PG) etc.

Anti-ripening agents: Anti-ripening food preservatives are generally used to preserve such food items that either contain fruit & vegetables as one of their ingredients or to preserve fruits and vegetables as such. As we know that the ripening in fruits is essentially an enzymatic process; promoted specifically by an enzyme called as ‘Polygalacturonase’ which acts on the pectin of the fruits and thus, makes them soft. The anti-ripening agents thus, act on this enzyme and inactivate the same. The best examples of such anti-ripening agents are:

• Citric acid,
• Ascorbic acid
• Disodium salt of ethylene diamine tetraacetic acid, acronymed as EDTA.

Anti-microbial preservatives: Such preservatives are the chemicals that can inhibit the growth of yeast, bacteria or moulds. In short, such food preservatives are meant to preserve the food items against whole lot of microbes that might be bacteria or fungus. The typical examples of such food preservatives may be stated as below:

• Sorbates,
• Esters of p-hydroxy benzoic acid,
• Sodium nitrite,
• Sodium sulphite,
• Calcium propionate and
• Benzoates etc…

(Note): Over and above these all, the chemical substances such as salt, vinegar (acetic acid), oils, spices and citric acid etc are also being used extensively to preserve the edible items like, jams, pickles, ketchups and squashes etc…Yet, above all, it has been the two chemical substances called as sodium metabisulphite and sodium benzoate that have remained to be the much favoured food preservatives..

Artificial sweetening agents: Ever since the discovery of very first artificial sweetener called Saccharin in the 1880s, the artificial sweeteners came into vogue and became quite popular as being zero calorie sweetening agents especially, amongst the weight conscious and diabetics. Today, some of the following artificial sweeteners are being extensively used in food items:

Saccharin, chemically called as ortho- Sulphobenzoic imide, shortly called as Orth-sulphobenzimide, is probably 500 times sweeter than the cane or table sugar called as Sucrose. It is interesting to note that the sweetest naturally occurring sugar, fructose, commonly called as fruit sugar as it is abundantly found in fruits and nectar or honey, has a sweetening index of 170 only whereas, the above artificially synthesized sugar, saccharin has a sweetening index of whooping 40,000 and thus, may be described as the sweetest of all artificial sweeteners. Sodium salt of saccharin is both water soluble and quite palatable at the same time. Saccharin is popularly used as a sweetening agent in the preparation of sweets meant for the diabetics.

Sucralose, an artificial sweetener that has been predicted to be a very good substitute of saccharine.

Aspartame* is a methyl ester of a dipeptide that is made of two amino acids called as phenylalanine and aspartic acid. Although, a quite popular artificial sweetener, but its use has been restricted to the cold food items because, it decomposes at baking or cooking temperatures thus, restricting its use to cold food & drinks only. It is said that aspartame breaks down in the body into menthol and one naturally occurring amino acid. *(Question asked in GS-pre-2011).

  Alitame: Another popular artificial sweetener that is described as the high potency artificial sweetener in the sense that the sweetness of the food items in which it is used becomes practically hard to control thus, it is rarely used as an artificial sweetener.

Dulcin (p-phenethyl urea), nitroanilines, acesulfame-potassium & DHC (dihydrochal cones) are other examples of artificial sweeteners.

Xylitol, a polyhydroxy compound exactly, a sugar alcohol used as a sweetener in sugarless bubble gums.

As stated above, it can thus be concluded that the artificial sweeteners are essentially zero calorie chemicals as they pass just unmetabolized through the human body and as such, have served a panacea especially, for diabetics…

Edible colours: The colors that can be added to the food items without their having any harmful side effects are known as edible colors. The purpose of adding the edible color into the food items is to enhance their eye appeal and of course, to compliment a definite flavor to the respective food item. However, in terms of their chemical composition and nature, the edible colors should be stable to acids, alkalies, light and high temperature etc. In terms of their origin & source, the edible colors may be of:

Natural origin: The commonly used edible colors of natural origin are:

Chlorophyll (green coloring matter present in all green leaves.)

Saffron (a product obtained from the saffron (Kesar) of commerce.)

Turmeric (a product obtained from the dried roots of Turmeric.)

Caramel (a product prepared by strongly heating the sugar.)

Cochineal or Caramine (a product that is basically a dye, obtained from the dried & dead bodies of the female insect called as Cochineal bug, a type of scale insect that feeds on Cacti and is a source of cochineal dye, locally called as Lahi. Rural womenfolk use this dye for Mahavar or Alta, including in some cosmetics as well. Cochineal is also used to color wine & certain drugs yet, medically; it finds a great use in the treatment of whooping cough & neuralgia. Interestingly, in the world, this bug is cultured on a commercial scale especially, in the countries like Mexico, Spain, Peru and Algiers etc…

Beta-Carotene (a product found and is obtained from the Carrots)

Alizarine & Indigo (dyes of plant origin).

Synthetic edible colors: The synthetic edible colors are also frequently used in various edible products. Some of them are being mentioned herein below:

Aniline dyes & azodyes are frequently used to replace the natural colors. In this regard,

Amaranth, aniline yellow and butter yellow etc are frequently used azodyes of which amaranth gives magenta color in aqueous medium. Some other widely used synthetic edible colors are being mentioned herein below in the tabulated form:

Common name of the colour	Actual colour it has
Erythrosine Allura red Sunset yellow Tetrazine Indigo line Carmoisine Ponceau	Bluish pink Yellowish red Reddish yellow Lemon yellow Deep blue Fast red Fast green.

Antifertility drugs: These are the chemical substances which are used to prevent unwanted pregnancies. These chemical substances are generally found in the form of anti-fertility pills or birth control pills or also called as contraceptive pills. Chemically, these contraceptive pills are nothing, but steroids which are exactly the analogues of the females two most important sex hormones called as estrogen and Progesterone. Structurally, a steroid molecule is a ringed structure, made up of four rings, designated as 3-cyclohexane rings & 1-cyclopentane ring. It is the cholesterol that is the precursor of above steroid hormones in human beings. Some of the birth control pills containing steroids are norgestol, ethinil, oestradiol & progestogens etc. Similarly, some of these oral contraceptive pills being known under the popular names as Mala-D & Saheli etc… 

Chemically, soaps whether, bathing or washing as such, are nothing, but essentially, sodium or potassium salts of fatty acids for example, sodium palmitate. This implies that there has certainly been a good amount of chemistry involved both in their constitution as well as in their synthesis. As we already know that the fatty acids that the soaps have one of their constituents are essentially the basic building blocks or so called monomeric forms of the fats or lipids. Thus, commercially the soaps are prepared by way of an alkaline hydrolysis of the fats or fatty acids say, for example, when oils (unsaturated fatty acids) are treated with alkalies such as NaOH or KOH, the resultant product that we get is a sodium or potassium salt of fatty acids which are essentially, but the soaps. Such molecules have characteristically two distinct ends what we call as water loving and water hating or repelling end. As such, these are also called as hydrophilic and hydrophobic ends. In chemistry, such dual ended molecules are described as amphipathic molecules. Being so, is what that explains the detergent like property of such molecules and hence, the cleansing action of soaps.

Owing to the very constitution of the soaps, they are associated with certain inherent limitations in their being used as a universal washing medium hence, today the synthetic detergents have come into being a preferred washing material over the soaps. The reason being that the detergents can be used comfortably in both hard and soft water because, they are capable of forming lather with either of the water types. And this is facilitated again by the very composition and constitution of the synthetic detergents that are predominantly the sulphonic acids and their calcium and magnesium salts which are easily soluble in water. In contrast to this, the soaps being fatty acids in their composition including their calcium and magnesium salts both are water insoluble in nature. This explains the popularity of synthetic detergents over the soaps.

What are synthetic detergents?

These are a class of cleansing agents which have all the properties of soaps so far as their washing ability is concerned, but they seldom actually contain any soap and thus, can conveniently be used in both soft and hard water. On the basis of their chemical composition, the synthetic detergents are being classified into three main categories as given below:

Anionic detergents: They are sodium salts of sulphonated long chain alcohols or hydrocarbons. For example, alkyl hydrogensulphates are an example of anionic detergents. These are prepared by treating long chain alcohols e.g. Lauryl alcohol, an alcohol of 12 carbon atoms with concentrated sulphuric acid followed by their being treated with alkali such as NaOH. The anionic detergents have largely been of two types called as Sodium alkyl sulphates whose typical example is sodium lauryl sulphate & Sodium alkylbenzenesulphonates which is exemplified by the most widely used domestic detergent called as sodium dodecyl benzenesulphonate, designated as (SDS).

Cationic Detergents: They are essentially the quarternary ammonium salts of amines with acetates, chlorides or bromides as anions. In these synthetic detergents, the cationic part is made up of a long hydrocarbon chain with a positive charge on nitrogen atom and hence, the name cationic detergent is given to them. For example, Cetyltrimethylammonium bromide or chloride are popular examples of cationic detergents that are used in hair conditioners. Noted also that the cationic detergents have remarkable germicidal properties and thus are expensive as compared to other synthetic detergents. In short, it can be said that in chemical composition, cationic detergents are invariably being the acetates or chlorides of quaternary amines…

Non-ionic detergents: As the name itself indicates, they do not contain any ion in their constitution. They are essentially described as the esters of high molecular mass alcohols with fatty acids. As such, they are exactly like the neutral fats called as triglycerides which are also the esters, but of a smaller, trihydroxy alcohol called as glycerol with three fatty acid chains.  Liquid dishwashing detergents are all non-ionic type of detergents although; their cleansing mechanism is exactly the same as that of the soaps. For example, one such detergent is formed when a saturated fatty acid called stearic acid is reacted with polyethylene glycol to form a non-ionic detergent what may be called as Polyethylene glycol stearate.

Why do synthetic detergents are preferred over soaps for washing purposes?

The answer gets quite obvious once, we understand the chemical composition or synthesis of the above two. While, the synthetic detergents are either alkyl hydrogensulphates (anionic) or ammonium salts (cationic) of calcium or magnesium. In either case, both are easily soluble in water and thus, can form lather both with hard and soft water. In contrast to this, the soaps, which are essentially the sodium salts of fatty acids which remain altogether insoluble in water particularly, in hard water, they end up forming precipitates. This is why that the soaps are generally used for testing the hardness of water because, they get precipitated as insoluble calcium and magnesium soaps in hard water. In a nut shell, the preference of synthetic detergents over the soaps for washing purposes may be supported by the simple fact that the former are being synthesized chemically from materials other than the animal fats, an unavoidable constituent of all soaps. Thus, we can now conclude that the advantages of detergents over the soaps can be supported on the following counts such as:

? They can work well even with acidic water.

? They can work well even with hard water.

? They can work far better than the soaps on the woolen garments and so on…

What are hydrocarbons?  In layman’s language, it seems sufficient to argue that the hydrocarbons are the important sources of energy. Otherwise, in chemistry terms, the term ‘hydrocarbon’ is itself self- explanatory which means that the hydrocarbons are the compounds of carbon and hydrogen only. Probably, the significance of hydrocarbons in our life is so much that we can not possibly conceive of our existence without them. For example, the most familiar terms such as LPG & CNG are neither alien to us, nor we anywhere are unfamiliar with their immense role in our daily life in their being the most popular kind of fuels. While, LPG is our kitchen cooking gas and CNG which stands for ‘compressed natural gas’ is an environment friendly automobile fuel introduced in the recent past in some of our metropolitan cities. Another hydrocarbon also gained currency in the recent past called LNG that stands for ‘liquefied natural gas’, is also an ideal automobile fuel, obtained from the liquefaction of natural gas. In short, whatever material or substance we are and have long been using as fuel, is nothing, but hydrocarbons. At the same time, hydrocarbons have also served the mankind in terms of their being used for the manufacture of synthetic polymers like polythene, polypropene & polystyrene etc. While, some of the higher hydrocarbons are being used as the starting materials for the manufacture of many dyes & drugs besides, some of them are being used as solvents for paints.

Traditionally, the hydrocarbons have been classified into following 3 categories on the basis of the type of C-C bonds present in them:

• Saturated hydrocarbons,
• Un-saturated hydrocarbons &
• Aromatic hydrocarbons. 

Saturated hydrocarbons: They are just like the saturated fats so far as their structure is concerned in the sense that all their carbon atoms are linked to each other through C-C single bonds. They are commonly called as ALKANES and are represented by their general formula as CnH2n+2, where ‘n’ refers to the number of carbon atoms and ‘2n+2’ stands for number of hydrogen atoms in an alkane. Noted that all these hydrocarbons are purely inert under normal conditions and thus, do not react with either acids or bases or any other reagent. This was the reason that they were earlier known as ‘Paraffins’ that is a Latin for (parum= little; affinis= affinity). The most important alkanes that have been a source of energy for the mankind ever since the dawn of human civilization are being mentioned herein below:

Methane, the very first member of alkane family and is a gas in terms of its physical state. This is generally found in coal mines and marshy places and is thus, also known popularly as marsh gas or sometimes, also as natural gas. Today, one of the green house gases contributing to green house effect, but remained very vital for causing the initial green house effect that made the evolution of life possible on this earth.

Propane/butane: This is the popular alkane that is what our common kitchen fuel, LPG is chemically known as.

Physical properties of alkanes: Noted that the first four alkanes i.e. from methane to butane are all gases. However, the next higher alkanes starting from carbon 5 up to carbon 17 are liquids and rest all; from carbon 18 onwards are all solids.  Alkanes are remarkable for complete burning when heated in the presence of air or oxygen to the consequence that they not only evolve a large amount of heat, but get completely burnt into carbon dioxide & water and thus, explains the logic of their being the universal fuels say for example, petroleum. If otherwise, these alkanes are not completely burnt that means, they are subjected to an incomplete combustion in the presence of insufficient air or oxygen, they give rise to what we call as ‘carbon black’ which then, is used for the commercial production of black ink, printer ink, black pigments as well as filters. Similarly, if higher alkanes are subjected to heating, but at extremely high temperatures, they get decomposed into smaller fragments of some lower alkanes or alkenes in a process called as ‘Pyrolysis’ or ‘cracking’ of alkanes. This is the process that is what used in the preparation of oil gas or so called petrol gas from that of the kerosene oil or petrol as such. For example, kerosene oil being an alkane is called as dodecane which upon heating gives a mixture of smaller alkanes during pyrolysis.

Unsaturated hydrocarbons: They are also like unsaturated fats in the sense that the unsaturated hydrocarbons shall invariably have at least, one double or triple C-C bond between any of the carbon atoms in their structure. As such, those unsaturated hydrocarbons that have a minimum of one C-C double bond are called as ALKENES. Since, due to the presence of a double bond, alkenes naturally have two hydrogen atoms less than the alkanes. Thus, their general formula may be pointed out as being CnH2n. whereas, those with a minimum of one C-C triple bond are called as ALKYNES.

Alkenes are also called as ‘olefins’ that means (oil forming) owing to the fact that the first member of the alkene family called ethylene or ethene (C2H4) was earlier found to form an oily liquid on being reacted with chlorine.

In terms of commercial significance, the most significant use or application of alkenes has been in the polymer industry. As who is not familiar with the polymers like polythene bags and polythene sheets, wherein, a very large number of ethene molecules are combined, end to end at substantially high temperature & pressure, may be in the presence of a catalyst and in a chemical process called as polymerization and thus, we obtain a polymer called polythene. Similarly, one more polymer of commercial significance called polypropene, also called as polypropylene that is obtained through polymerization of a little higher alkene called as propene. Polypropene is an important polymer, used for the manufacture of milk crates, plastic buckets and moulded furniture items.

ALKYNES are also unsaturated hydrocarbons just like the alkenes, noted for having a minimum of one C-C triple bond between any two carbon atoms in their molecular structure. Since, the alkynes are noted for having a triple bond thus, the number of hydrogen atoms is even more less in alkynes as compared to alkenes and alkanes. Hence, their general formula comes out to be as CnH2n-2. The first stable member of alkyne series is called as ethyne which is rather, called popularly as acetylene.  Acetylene is our common welding gas, used for arc welding purposes in the form of oxyacetylene flames. Otherwise, alkynes are the important starting materials for the synthesis of a large number of organic compounds.

Aromatic hydrocarbons: These hydrocarbons are also known as ‘arenes.’ However, the name aromatic hydrocarbons has been imparted to them owing to the presence of a distinct aroma or smell present, without any exception in these compounds. The word ‘aromatic’ (from Greek; aroma= pleasant smelling). Structurally, all these compounds are noted for having a benzene like structure, a hexagonal structure marked with the presence of alternate single and double bonds inside the hexagon, what we call a benzene ring. A benzene ring, denoted by molecular formula C6H6, is a highly unsaturated compound and owes many remarkable organic synthesis reactions to its unsaturated nature. But it must also be noted that all aromatic hydrocarbons do not necessarily have a universal benzene like structure in them. Instead, we do have such aromatic hydrocarbons in which rather than a benzene ring, some other highly unsaturated ringed structures are present. Thus, we have a two fold classification of aromatic hydrocarbons called as Bezenoids and non-Benzenoids. In the former category, we may cite many familiar examples of compounds such as Aniline, famous dye constituent or Phenol, a popular disinfectant. Similarly, in the latter category, we may exemplify compounds like Naphthalene and Biphenyl etc.

Although, Benzene was first of all isolated by Michael Faraday in the year 1825, its present applicable cyclic structure was proposed by one German chemist named Friedrich August Kekule somewhere, around 1865. Benzene on a commercial scale is isolated from coal tar, but it can also be prepared in the laboratory as such by various methods.

For a layman, the aromatic compounds or benzene derivatives can be understood easily by having a reference to the popular and quite familiar naphthalene balls which we commonly use in toilets or urinals and for the preservation of our woolen clothes from the moths, just because of their characteristic smell and unique moth repellent property. Similarly, the famous crop pesticide, BHC is also an aromatic compound, prepared by subjecting benzene to a strong beam of UV-lights while benzene is being reacted with chlorine. BHC is commercially called as Gammaxane or Lindane. In the same vein, DDT, is another aromatic compound being used as an insecticide although, most of the countries have banned it today owing to its role in ‘Biomagnification.’

Bad effect of aromatic compounds: Although, aromatic compounds including benzene have wider industrial applications and use as some of them have been mentioned above. Yet, all of them unfortunately,been noted for their carcinogenicity and toxicity thereby, limiting their profound use and application. In fact, benzene and almost all polynuclear hydrocarbons containing more than two benzene rings fused together have been found to be not only toxic, but are said to possess cancer producing (carcinogenic) property. Such polynuclear hydrocarbons are generally formed on incomplete combustion of organic materials like tobacco, coal and petroleum etc. For example,*benzopyrene, a substance found in tobacco smoke has been found to be a potential cancerous substance. Similarly, another carcinogenic substance, found in cigarette smoke, is a polycyclic hydrocarbon called as N-nitroso dimethylene. Such polycyclic or polynuclear hydrocarbons formed on incomplete burning of organic materials enter into human body and undergo various biochemical reactions and finally, end up damaging human DNA and thus, become a cause of cancer. Some of other such polycyclic hydrocarbons having carcinogenic property are mentioned herein below in a tabulated form:

 

Name of the Polycyclic compound	Number of benzene rings fused together.
1,2-Benzathracene 3-Methylcholanthrene *1,2-Benzpyrene 1,2,5,6-Dibenzanthracene 9,10-Dimethyl-1,2-benzanthracene.	Four benzene rings. Four benzene and one cyclopentane ring. Five benzene rings. Five benzene rings. Four benzene rings.

Acetaldehyde	An organic compound used as an antiseptic in nose troubles.
Acetaldehyde ammonia	A rubber accelerator.
Acetone	For storing acetylene.
Acetic anhydride	In the preparation of dyes, acetate rayon and aspirin.
Ammonia NH3	In making HNO3, NaHCO3, (NH4)2SO4 and amm. Calcium sulphate (both fertilizers), NH4NO3 (explosive), artificial silk; as a cleaning agent for removing grease in dry cleaning.
Alumina, Al2O3	As a refractory material, cement bauxite + lime), abrasive, for preparing artificial gems, in chromatography.
Alum, K2SO4. Al2(SO4)3. 24H2O	In purification of water, tanning of leather, as mordant in dyeing, as a styptic to arrest bleeding, for sizing of paper.
Ammonal	A mixture of ammonium nitrate and aluminum powder, used as an explosive.
Bleaching Powder, CaOCl2	For making wood unshrinkable, in the manufacture of chloroform, Bleaching agent, sterilization of drinking water.
Butter of tin (Oxymuriate of tin), SnCl4. 5H2O	as Mordant.
Basic lead carbonate, white lead, 2PbCO3, Pb (OH) 2	In white paint.
Calcium ammonium nitrate (CAN)	Nitrogen fertilizers.
Chlorine, Cl2	Bleaching agent, purification of drinking water, as germicide, as disinfectant in swimming pools, preparation of domestic antiseptic solution (NaOCl), bleaching power, chlorates, DDT, poisonous gases like COCl2, tear gas and mustard gas.
Calcium carbonate, CaCO3	Used as limestone for the manufacture of lime and as a flux; as marble for building purposes and in the production of CO2; as chalk in paints and distempers and in the production of CO2 ; as precipitated chalk in tooth pastes and powders, in medicines for indigestion.
Carbon black	In making printer’s ink, black paints and filler in rubber.
Carborundum, SiC	As an abrasive.
Carbon monoxide, CO	Production of water gas and producer gas, in extraction of iron and nickel, reducing agent.
Carbon dioxide, CO2	As a fire extinguisher, refrigerant (as dry ice), for artificial respiration as (carbogen), manufacture of aerated water, white lead and Na2CO3 (Solvay process).
Copper sulphate, CuSO4, 5H2O (Blue vitriol)	In Bordeaux mixture (A fungicide), electroplating, electrotyping, dyeing calico printing, detecting moisture, preparing Fehling solution & as an insecticide.
Chloroprene	In the manufacture of neoprene (a synthetic rubber).
Chloroform	Preservative for dead bodies, anaesthetic, in the preparation of chloropicrin (insecticide) and chloretone (hypnotic).
Carbon tetrachloride, CCl4	As fire extinguisher under the name pyrene, solvent, fumigant, in the elimination of hook works (antihelmenthic).
D.D.T Dichlorodiphenyltrichloroethane	An insecticide.
Ethyl acetate	In perfumes, in skin diseases.
Ethyl alcohol	As solvent, as a fuel in spirit lamps, in spirit levels, as a beverage, power alcohol (alcohol + petrol + benezene), and antifreezer for automobile radiators.
Ferric oxide, Fe2O3	As a red pigment, as a catalyst, as polishing powder.
Ferric Chloride (Tincture ferriperchloride), FeCl3	As an astringent and antiseptic& in block making.
Freon (dischlorodifluoro methane) CCl2F2	A refrigerant and propellant in aerosols.
Formaldehyde	In the preparation of bakelite, urotropine, in silvering of mirrors; its 40% aqueous solution known as formalin is used as preservative for biological specimens.
Formic acid	In tanning for removing lime from hides, as a reducing agent.
Green Vitriol (Hara Kansa),	As mordant in dyeing, as insecticide, in organic analysis, in the preparation of blue black ink.
Heavy water (D2O)	A moderator in nuclear reactor.
Hydrogen peroxide	Bleaching agent, oxidizing agent, restoring colour of lead painting blackened by H2S, antiseptic, germicide, propellent or fuel in rockets, etc.
Hydrogen sulphide, H2S	Reducing agent, laboratory reagent.
Hypo, Na2S2O3. 5H2O	Fixing agent in photography, as an antichlor, in volumetric analysis & in the extraction of Au and Ag from ores.
Iodine, I2 and Kl	are used in treating goiter; for increasing production of eggs.
Iso-octane (2, 2, 4-trimethyl pentane)	Increases the anti-knock qualities of petrol.
Iodoform	As an antiseptic.
Lunar caustic, AgNO3	In making inks and hair dyes, silvering of mirrors, as a caustic in surgery. AgX (except Agl) are used in photography.
Magnesium metal	Preparation of Grignard reagent (RMgX) used in organic chemistry, as a fuse in aluminothermic process, in flash light in photography.
Magnesic, MgO	An antacid, as refractor lining, as basic lining, as insulator, rubber filler, Sorrel’s cement (MgCl2, 5MgO, xH2O), used in filing teeth and as substitute for tiles.
Mustard gas,	In Warfare as warfare killer gas.
Nitrous oxide (Laughing gas), N2O	As propellant gas, anaesthetic especially, in tooth extraction.
Nitric oxide, NO	Intermediate HNO3 manufacture, catalyst in lead chamber, in detection of oxygen.
Nitrous acid, HNO2	Used in preparation of azo dyes.
Nitric acid, HNO3	In making explosives (T.N.T., picric acid, nitroglycerine, dynamite and gun cotton), fertilizers (ammonium nitrate, calcium nitrate), artificial silk, dyes, drugs, perfumers; in the purification of silver and gold; as a solvent for etching designs or names upon copper& brass and bronze articles.
Oxygen, O2	Oxygen + CO2 or O2 + Helium for artificial respiration; O2 as liquid O2 + finely divided C as a substitute of dynamite; liquid O2 as rocket fuel; oxy-hydrogen and oxyacetylene flames are used for cutting and welding purposes.
Ozone, O3	As sterilizing agent for water, for improving the atmosphere of crowded places, mild bleaching agent for detecting the position of double bonds, for preparing KMnO4 from K2MnO4, artificial silk and synthetic camphor.
Oil of vitriol, H2SO4	In preparing dyes, fertilizers, detergents, explosive, lead storage batteries, dehydrating agent & pickling agent.
Phosphorus	Red P in match industry, white as rat poison.
Potassium metal	Used in photoelectric cells.
Potassium carbonate, K2CO3	Soft soap, hard glass, fusion mixture, washing wool.
Potassium bicarbonate, KHCO3	Used in medicine and baking powder.
Potassium sulphate, K2SO4	As fertilizer, in potash alum and glass, as a purgative in medicine.
Plaster of Paris (POP), CaSO4. 1/4H2O	For setting broken and fractured bones, for making models, for producing moulds for industries such as pottery and ceramics.
Phenol	Antiseptic; in the preparation of aspirin (antipyretic and analgesic), picric acid (explosive), salol (intestinal antiseptic), phenolphthalein (indicator), bakelite (plastic used to make electric switches, buttons, etc.)
Paraldehyde, (CH2O) n	A hypnotic and sporofic.
Phenacyl Chloride. C6H6COCH2CI	As a lachrymator to disperse mobs
Phosgene (COCl2)	A poisonous gas used in warfare.
Quick lime, CaO	Bleaching powder, slaked lime, lime colors, cement and calcium carbide, purification of sugar and coal gas, softening of water, a basic lining.
Sulphur	In match industry and fireworks, vulcanization of rubber, disinfectant for houses, skin medicines and in preparing sulphur dyes.
Sulphur dioxide, SO2	Bleaching agent, antichlor, solvent (liquid SO2).
Sulphur trioxide, SO3	Manufacture of H2SO4 called as oleum; for drying gases.
Sodium and potassium bromides	Sedatives, AgBr are used in photography.
Sodium metal	Preparation of TEL, sodium amalgam, on sodium vapour lamp, heat transfer medium in nuclear reactors, Na-K alloy (liquid at room temperature) is used in high temperature (thermometers used for finding temperature above the b.p. of mercury.
Sodium peroxide, Na2O2	Oxidizing agent, source of oxygen under the name of axone, purification of air, bleaching agent (soda bleach – Na2O2, dilute HCl).
Sodium hydroxide, NaOH	For mercerizing cotton to make cloth unshrinkable, manufacture of soap.
Sodium carbonate, washing soda, Na2CO3	In laundries, manufacture of glass, fusion mixture (Na2CO3 + K2CO3).
Sodium bicarbonate, Baking soda, NaHCO3	Preparation of baking powder, seildlitz powder, effervescent drinks and fruits salts, in fire extinguishers & as antacid.
Sodium sulphate, Galuber’s salt	Craft paper, window glass, mild laxative.
Slaked lime, Ca (OH) 2	Bleaching powder, caustic soda and soda lime, white washing, softening of water.
Stannous chloride	Mordant in dyeing (under the name of tin salt) and as a reducing agent.
Silver metal	In coins, ornaments, filing teeth (silver-alloy), medicines, silver plating.
Tin metal	Tin foil is used for wrapping cigarettes, confectionery and for making tooth-paste tubes.
Trilead tetraoxide, Minimum, Red lead, Pb3O4	In paint, silver mirrors, lead glass flint glass matches and oxidizing agent.
Tear gas (CCI3.NO2), also called as Chloropicrin	Used to disperse mobs.
Vinyl cyanide (Acrylonitrile), CH2 = CHCN	In manufacture of Orlon, (synthetic fibre) and buna – N (synthetic rubber).
Zinc white, ZnO	As white pigment under the name of zinc white or Chinese white, as zinc ointment, as filler in rubber industry & white shoe polish.
Zinc Sulphide, ZnS	In lithopone, x-ray screens and in luminous paint of the dials of watches

.            

We as humans have long been familiar and accustomed to the convention of using either short names or abbreviations in our daily life in place of lengthy names in order to facilitate the ease with which they could be remembered or recalled. Say for example, we would always prefer to use, remember or write say, USA instead of using United States of America or for that matter, GPO in place of using or writing General post Office and so on…

 In the same way, the science of Chemistry ever since its inception, has also invented & customized the use of certain discrete symbols & notations that appear and written in the form of alphabets to represent the full name of the elements or compounds. This way, they have not only facilitated in their being remembered or recalled, but indeed have constituted altogether a new language of the subject what we call as the language of Chemistry; a language which talks in & through signs & symbols. Given thus, we can say that:

A symbol is defined as an abbreviation or shorthand sign for the full name of an element.

In fact, in the practical sense, one or more letters are used to write the symbol of an element. For example, oxygen is represented by the letter ‘O’, while Ca (two letters) is written for calcium. The method of naming the substances is called Chemical nomenclature while the representation of the substances with the help of a symbol is called as Chemical notation.

SYMBOLIC ALLOTMENT

It was    J.J. Berzelius (1811) who suggested for the first time, a method of representing elements using the English letters (capital as well as small). The first letter of the symbols is always capital while the second one is always small. For example, symbol of cobalt is Co and not CO because CO represents altogether a different molecule called as carbon monoxide.

Given below is a list of the elements, whose symbols are written using the first capital letter only.

Table 1, showing: First Capital Letter representing the name of the Element

Similarly, two letters are also being used to represent most of the elements.

Element	Symbol
Boron	B
Carbon	C
Fluorine	F
Hydrogen	H
Iodine	I
Oxygen	O
Phosphorus	P
Sulphur	S
Uranium	U
Vanadium	V

 

 Given below is the list of the elements whose symbols are written using two letters, but again the first letter shall always be in capital.

 

Table 2, showing: Two Letters representing the name of the Element

Element	Symbol	Element	Symbol
Aluminum	Al	Magnesium	Mg
Argon	Ar	Manganese	Mn
Arsenic	As	Molybdenum	Mo
Astatine	Ba	Nickel	Ni
Barium	Be	Neon	Ne
Beryllium	Bi	Strontium	Sr
Bismuth	Br	Silicon	Si
Bromine	Cd	Palladium	Pd
Cadmium	Ca	Platinum	Pt
Calcium	Cl	Radium	Ra
Chlorine	Cr	Radon	Rn
Chromium	Co	Rubidium	Rb
Cobalt	Co	Zinc	Zn
Gallium	Ga	Selenium	Se
Helium	He	Silicon	Si
Lithium	Li	Tellurium	Te

 

Table 3 below showing: A list of the elements whose symbols are derived from Latin names or words.

Element	Latin Name	Symbol
Antimony	Stibium	Sb
Copper	Cuprum	Cu
Gold	Aurum	Au
Iron	Ferrum	Fe
Lead	Plumbum	Pb
Mercury	Hydrargyrum	Hg
Potassium	Kalium	K
Silver	Argentum	Ag
Sodium	Natrium	Na
Tin	Stannum	Sn
Tungsten	Wolfram	W

 

Table 4 below showing: A list of Elements after the names of the Scientists.

Element	Name of the Scientist	Symbol
Curium	Madam Curic	Cm
Einsteinium	Albert Einstein	Es
Fermium	Enrico Fermi	Fm
Nobelium	Alfred Nobel	No
Mendelevium	Mandeleef	MD

 

Table 5 below showing:  Name of the Elements after the name of the Countries and Laboratories/Universities/Institutes.

Element	Country or Laboratory	Symbol
Berkelium	City of Berkley	Bk
Californium	University of California	Cr
Polonium	Poland	Po
Americium	America	AM
Ruthenium	Russia	Ru
Germanium	German	Ge

 

Table 6 below showing: Elements after the name of the Planets

Element	Name of the planet	Symbol
Uranium	Uranus	U
Neptunium	Neptune	Np
Plutonium	Pluto	Pu